During the present investigations of seasonal prevalence of gastrointestinal myiasis producing larvae recovered from 447 human stools obtained from Govt. of Sind Medical Labs, Karachi, 8 species of dipterous larvae belonging to 6 genera were recorded. The larvae occurred singly or in a combination of 2 or 3 species. Of the 24 combinations of different species, 5 had single species, 17 had 2 species and 2 had 3 species. The seasonal prevalence of larvae were also studied.